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. Author manuscript; available in PMC: 2015 Dec 14.
Published in final edited form as: Phys Chem Chem Phys. 2010;12(20):5353–5368. doi: 10.1039/b925496j

Figure 2.

Figure 2

ESR spectra of: authentic (A) 1-Me-G•+ (red) and (B) 1-Me-G(N2-H)• (blue) obtained from glassy (7.5 M LiCl in D2O) samples of 1-Me-Guo via annealing at 155 K in the dark. The match of these experimentally observed spectra of 1-Me-G•+ and 1-Me-G(N2-H)• as benchmarks with those obtained using one-electron oxidized 1-Me-Guo (black) at pD ca. 6.8 first annealed at 155 K and further annealed at 175 K indicate that for one-electron oxidized 1-Me-Guo at pD 6.8, annealing at 155 K produces first the cation radical 1-Me-G•+ and further annealing at 175 K leads to its deprotonation to form G(N2–H)•. From these results, we estimate the pKa of 1-Me-G•+ as ca. 6.6 in our system (7.5 M LiCl in D2O at low temperature) as shown in Figure (C).